Curbs and debris have never been a tyre’s best mate, however, today most of the tyres prevent accidental damage due to the thicker rubber mounded at key locations on their sidewalls. It reduces damage to the tyres/wheels rubbing against curbs or turning sharply out of a driveway.
Most of the standard tyres do not really come with any kind of protectors because they are continuously mounted on steel wheels. Initially, it may be seen as an omission but it's actually done to accommodate the reality that most steel wheels use hubcaps to provide a more desirable appearance. The absence of a rim protector provides flexibility in the hubcap styling and design fastened to the wheel.
The tyres that come with the feature of rim protectors incorporate various designs. Most of these features a raised rib adjacent to the bead section on their inferior side walls or a deeply recessed bead area to partially envelope the wheel flange however other tyres feature ribs at the tyre’s maximum section width (distance between the tyre’s sidewalls and the widest part of the tyre).
The tyres that feature a raised rib adjacent to the bead area and the deeply recessed beaded area are engineered to protect the low profile tyres and exy alloy wheels from any accidental curb damage whereas the tyres coming with the raised rib or molded recess will thwart the use of wheel covers, this isn't really a problem since these tyres are customarily used on the vehicles equipped with alloy wheels. The rim protectors are helpful in shielding the tyre and wheel bead area from the debris in light truck off-road applications moreover it also resists damage inflicted by rocks, tree stumps and other off-road of obstacles.
tyres that are comprised of one or more raised ribs are usually found on delivery van and trailers at their maximum section width. The extra rubber thickness of the raised ribs at the widest point of the tyre resists any damage to the side walls and reduces the amount of rubber that will be worn away before repeated curves scuffing cuts or exposes the tyre’s internal cords.
Whether their manufacturers claim them to be "maximum flange shields", "rim protectors" or "scuff guards", the purpose of all rim protectors is ultimately the same. They are aimed to sacrifice themselves in order to protect the tyres internal side wall structure and alloy wheels upon which they are mounted.